The present invention relates generally to endoscopic devices and, more specifically, to an endotracheal intubation device having steering capability to allow the steerable distal end of the shaft of the device to be moved to a number of different angular positions to help direct the device through normal and pathologic patient anatomy. In use, an endotracheal tube is co-axially placed over the shaft of the endotracheal device so that the distal end of the endotracheal tube can be properly inserted into the trachea. The shaft of the current device may be of different rigidities, i.e., either flexible, like a conventional endoscope (colonoscope, bronchoscope, etc.) or malleable, namely, it can retain its shape once bent. Unlike other organs (colon, ureter, etc.) the oropharynx does not provide a tightly conforming conduit through which an endoscope can be passed. The flexible embodiment of the endoscope herein described can be used with a unique pre-formed conduit which allows for passage of this endoscope, with an endotracheal tube mounted on it, into the retropharyngeal space. The steerable distal end of the shaft can then be steered to position the endotracheal tube into the trachea. The present invention is also directed to methods for performing tracheal intubation.
In both medical emergencies, trauma, and as part of general anesthesia for surgery, a breathing tube is positioned in the airway of a patient. Endotracheal intubation, usually referred to as intubation, is the placement of a flexible plastic tube, an endotracheal tube or ETT into the trachea (windpipe) of the patient to maintain an open airway and to serve as a conduit through which to administer certain gases, including oxygen and anesthetic gases, directly to the lungs. It is frequently performed in critically ill, injured or anesthetized patients to facilitate ventilation of the lungs, including mechanical ventilation, and to prevent the possibility of asphyxiation or airway obstruction.
Human anatomy does not permit unaided visualization of the airway beyond the tongue. A tube passed blindly through the mouth or nose is likely to end up in the esophagus, leading to the stomach, rather than into the trachea, leading to the lungs. A variety of tools exist for performing this procedure under direct vision, which is usually performed by highly trained medical professionals in a hospital or pre-hospital setting. For the anatomical reasons stated above, namely that there is no direct line of sight from outside the mouth to the trachea, intubation involves the use of a viewing instrument of one type or another which allows the tongue to be retracted and the airway structures identified under direct vision. A modern conventional laryngoscope is most often used for intubation and consists of a handle containing batteries that power a light to visualize the target site, namely the vocal cords, which are the entry to the trachea, and a set of interchangeable blades, which are either straight or curved. With the patient on their back (supine) and the practitioner behind the patient's head, the laryngoscope is initially inserted into the patient's oral cavity. The laryngoscope blade is designed to control and move the tongue and other internal structures out of the way so that the airway can be positively identified. The vocal cords of the patient are the entry point to the windpipe (trachea) and lungs and represent the target destination through which the breathing tube (referred as an endotracheal tube) is advanced. The endotracheal tube is basically a flexible catheter that is inserted into the trachea for the primary purpose of establishing and maintaining an open and unobstructed airway. As above, endotracheal tubes are used for airway management in the settings of general anesthesia, critical care, mechanical ventilation and trauma.
Conventional intubation begins by introducing an instrument, usually a laryngoscope, into the patient's oral cavity to move the patient's tongue out of the way so that the patient's vocal cords can be identified. In practice, however, there may be anatomical anomalies and physical variations among patients which often do not permit easy direct visualization of the vocal cords. This leads to multiple attempts using different equipment. Failure to establish an airway in critically ill or anesthetized patients may lead to hypoxia (lack of oxygen), brain damage or even death in five minutes.
A conventional intubating stylet can be used in conjunction with the endotracheal tube and laryngoscope and is designed to be inserted into the internal lumen of the endotracheal tube to make the endotracheal tube, which is manufactured in a shallow “C” shape, conform better to the individual patient's anatomy and thereby facilitate steering the endotracheal tube into the trachea. This conventional stylet is in common use and can be made from a malleable metal wire, such as copper or aluminum, which allows the practitioner to impart a desired bend or shape, for example a tight “C” or a sharply angled or “hockey stick” shape, to the stylet and therefore to the overlying endotracheal tube. The stylet is typically used when the medical practitioner anticipates a difficult intubation.
During the intubation procedure, the practitioner usually holds the laryngoscope in one hand while holding the endotracheal tube and stylet, if used, with the other. The laryngoscope is used to retract the tongue and other internal structures, including the epiglottis, leading to direct visualization of the vocal cords. Once the vocal cords have been positively identified, the practitioner advances the endotracheal tube/stylet assembly so that the distal end of the endotracheal tube is inserted gently through the vocal cords and into the trachea. The stylet is then removed, leaving the endotracheal tube in the trachea and ventilation of the lungs can then be established.
While identification of the vocal cords under direct vision as described above is normally routine, there may be internal anatomical or pathological obstructions that are not apparent on visual inspection of the patient's surface anatomy. Multiple attempts at intubation may result in injury to teeth, epiglottis and vocal cords. Bleeding may result, with even less ability to visualize the airway and sometimes to obstruction of the airway, leading to hypoxia.
The endotracheal tube has a proximal fitting, or t-piece, designed to be connected to a source of pressurized gas, such as oxygen. The endotracheal tube may include an inflatable balloon (referred to as a cuff) at its distal end which is inflated once the endotracheal tube has been properly positioned within the trachea. The distal tip of the endotracheal tube should be positioned above the carina (before the trachea divides to each lung) so that both lungs can be ventilated equally. After the endotracheal tube has been inserted into the trachea, the balloon cuff is inflated to seal the airway and allow oxygen and other gases to be pumped into the lungs. This inflated balloon not only prevents retrograde leakage of respiratory gases from the lungs but also protects the tracheobronchial tree from undesirable material such as stomach acid or secretions passing anterograde and into the lungs. The proximal end of the endotracheal tube can then be secured to the face of the patient close to the mouth and connected to the t-piece, anesthesia breathing circuit, bag valve mask device, or a mechanical ventilator. Once in place, the endotracheal tube is used to ensure the adequate exchange of oxygen and carbon dioxide, to deliver oxygen in higher concentrations than found in air, or to administer other gases such as anesthetic gases, helium, nitric oxide, or xenon.
Because it is and invasive and extremely uncomfortable procedure, intubation is most frequently performed after induction of general anesthesia. Furthermore, a neuromuscular blocking (paralyzing) drug is usually given to relax the muscles of the head and neck and facilitate intubation. However, this means that the patient has now lost his ability to breathe spontaneously and therefore ventilation must be supported by the practitioner. At this point inability to intubate or provide ventilation of the lungs can lead to grave consequences, and is the leading cause of medical malpractice claims against anesthesiologists.
As noted above, difficult tracheal intubation can be associated with complications of varying severity. There may be broken teeth or lacerations of the tissues of the upper airway. It can also be associated with potentially fatal complications such as pulmonary aspiration of stomach contents which can result in a severe and sometimes fatal chemical aspiration pneumonitis. Unrecognized intubation of the esophagus, instead of the trachea, leading to fruitless ventilation of the stomach, can lead to potentially fatal anoxia. Because of this, the potential for difficulty or complications due to the presence of unusual airway anatomy or other uncontrolled variables is carefully evaluated before undertaking tracheal intubation. However, normal surface anatomy is no guarantee of favorable internal anatomy and easy intubation, so alternative strategies for securing the airway must always be readily available.
Endotracheal intubation using a direct laryngoscope is usually a relatively easy procedure to perform by trained personnel. However, difficult cases sometimes require specially made devices to provide alternative methods for intubation. Some laryngoscopes feature specially shaped blades and the use of fiber- or video-optics for indirect visualization where direct visualization is not possible. Fiber optic laryngoscopes have become increasingly available and commonly used since the 1990's. In contrast to the conventional laryngoscope, which only afford a direct line of sight, these devices allow the medical practitioner to “see around the corner” and indirectly view the larynx. This may provide a significant advantage in those situations where the practitioner cannot obtain a direct view of the larynx and needs to see around an acute bend in the airway, caused for example by a large tongue, short lower jaw, small mouth or protruding teeth. Video laryngoscopes are specialized fiber optic laryngoscopes that use a digital video camera sensor to allow the operator to view the glottis and larynx on a video monitor.
One of the problems associated with conventional intubation devices, such as the stylet, includes the fact that once the stylet is pre-shaped by the practitioner, it cannot be additionally bent while it is placed within the patient's oral cavity. If the initial shape imparted to the stylet does not allow the endotracheal tube to be properly maneuvered into the trachea, the practitioner must remove the stylet (and mounted endotracheal tube) from the patient's pharynx, re-bend the stylet/endotracheal tube assembly to a more favorable shape, and then reintroduce the assembly back into the patient's pharynx. These steps may have to be repeated again if the stylet is not bent into the proper configuration. Also, the practitioner needs to withdraw the laryngoscope from the patient's oral cavity when the stylet has to be re-shaped, and then re-insert the laryngoscope into the patient's oral cavity followed by the newly-formed stylet and endotracheal tube. Therefore, current conventional medical devices can increase the time needed to intubate the patient and can cause the practitioner to devote considerable effort in order to properly intubate the patient. Therefore, there is a continued need for intubation devices for use by practitioners and clinicians that are highly reliable, relatively easy to use and are able to synchronize visualization of the vocal cords with endotracheal tube placement. The present invention satisfies these and other needs.